On 12/09/2014 06:27 AM, Dongsheng Yang wrote:
Currently, for pre_alloc or delay_alloc, the bytes will be accounted in space_info by the three guys. space_info->bytes_may_use --- space_info->reserved --- space_info->used. But on the other hand, in qgroup, there are only two counters to account the bytes, qgroup->reserved and qgroup->excl. And qg->reserved accounts bytes in space_info->bytes_may_use and qg->excl accounts bytes in space_info->used. So the bytes in space_info->reserved is not accounted in qgroup. If so, there is a window we can exceed the quota limit when bytes is in space_info->reserved.Example: # btrfs quota enable /mnt # btrfs qgroup limit -e 10M /mnt # for((i=0;i<20;i++));do fallocate -l 1M /mnt/data$i; done # sync # btrfs qgroup show -pcre /mnt qgroupid rfer excl max_rfer max_excl parent child -------- ---- ---- -------- -------- ------ ----- 0/5 20987904 20987904 0 10485760 --- --- qg->excl is 20987904 larger than max_excl 10485760. This patch introduce a new counter named may_use to qgroup, then there are three counters in qgroup to account bytes in space_info as below. space_info->bytes_may_use --- space_info->reserved --- space_info->used. qgroup->may_use --- qgroup->reserved --- qgroup->excl With this patch applied: # btrfs quota enable /mnt # btrfs qgroup limit -e 10M /mnt # for((i=0;i<20;i++));do fallocate -l 1M /mnt/data$i; done fallocate: /mnt/data9: fallocate failed: Disk quota exceeded fallocate: /mnt/data10: fallocate failed: Disk quota exceeded fallocate: /mnt/data11: fallocate failed: Disk quota exceeded fallocate: /mnt/data12: fallocate failed: Disk quota exceeded fallocate: /mnt/data13: fallocate failed: Disk quota exceeded fallocate: /mnt/data14: fallocate failed: Disk quota exceeded fallocate: /mnt/data15: fallocate failed: Disk quota exceeded fallocate: /mnt/data16: fallocate failed: Disk quota exceeded fallocate: /mnt/data17: fallocate failed: Disk quota exceeded fallocate: /mnt/data18: fallocate failed: Disk quota exceeded fallocate: /mnt/data19: fallocate failed: Disk quota exceeded # sync # btrfs qgroup show -pcre /mnt qgroupid rfer excl max_rfer max_excl parent child -------- ---- ---- -------- -------- ------ ----- 0/5 9453568 9453568 0 10485760 --- --- Reported-by: Cyril SCETBON <cyril.scet...@free.fr> Signed-off-by: Dongsheng Yang <yangds.f...@cn.fujitsu.com> --- fs/btrfs/extent-tree.c | 25 ++++++++++++++++++- fs/btrfs/inode.c | 22 +++++++++++++++- fs/btrfs/qgroup.c | 68 +++++++++++++++++++++++++++++++++++++++++++++++--- fs/btrfs/qgroup.h | 4 +++ 4 files changed, 113 insertions(+), 6 deletions(-) diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c index 014b7f2..9eaf268 100644 --- a/fs/btrfs/extent-tree.c +++ b/fs/btrfs/extent-tree.c @@ -5500,8 +5500,13 @@ static int pin_down_extent(struct btrfs_root *root, set_extent_dirty(root->fs_info->pinned_extents, bytenr, bytenr + num_bytes - 1, GFP_NOFS | __GFP_NOFAIL); - if (reserved) + if (reserved) { + if (root->fs_info->quota_enabled)
You already have this check in btrfs_qgroup_update_reserved_bytes, just call it unconditionally everywhere in this patch. Otherwise this looks good, thanks,
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